1. Field of the Invention
The present invention relates to a synchronous rectifier applied to a power converter and an operation method thereof, and particularly to a synchronous rectifier and an operation method thereof that can generate a supply voltage independent of an output voltage of a secondary side of the power converter and do not need an auxiliary winding of a primary side of the power converter.
2. Description of the Prior Art
When an alternating current (AC)/direct current (DC) power converter is applied to a charge system, sometimes an output voltage of a secondary side of the AC/DC power converter is decreased to very low potential because the charge system needs to full charge an electronic product electrically connected to the charge system. When the output voltage of the secondary side of the AC/DC power converter is decreased to very low potential, if a synchronous rectifier of the secondary side of the AC/DC power converter needs the output voltage to act as a supply voltage, meanwhile the synchronous rectifier cannot operate normally because the output voltage is decreased to very low potential, resulting in conversion efficiency of the AC/DC power converter being reduced and the AC/DC power converter having serious heating problem.
The prior art utilizes an auxiliary voltage generated by an auxiliary winding of a primary side of the AC/DC power converter to act as the supply voltage of the synchronous rectifier, but the auxiliary winding will increase cost of the AC/DC power converter and design complexity. Therefore, for a designer of the synchronous rectifier, how to improve the above mentioned disadvantages of the prior art becomes an important issue.